Sewing machine with needle position control means



P 1965 w. M. DE JONG 3,204,592

SEWING MACHINE WITH NEEDLE POSITION CONTROL MEANS Filed Nov. 19, 1962 INVENTOR W/LH'fLMUS MAR/A DE JONG ATTORNEYS United States Patent 3,204,592 SEWING MACHINE WITH NEEDLE POSITIGN CONTROL MEANS Wilhelmus Maria tie long, flheghemstraat 21, Amsterdam, Netherlands Filed Nov. 19, 1962, Ser. No. 238,449

Claims priority, application Netherlands, Nov. 20, 1961,

4 Claims. (Cl. 1122l9) The invention relates to a sewing machine, more particularly an industrial sewing machine in which the main spindle can be driven via a rope or belt pulley or like means mounted thereon by a driving motor provided with automatic brake means while provisions are made for causing the machine to stop in a definite position, more particularly with the needle in the highest position.

Such sewing machines are already known. With these machines, for obtaining the stopping in a definite position, a special motor is used which per se is provided with means whereby it always stops in a definite position after being brought to action, while, for obtaining a right stop position of the sewing machine, a so called synchronizer is further arranged on the main spindle and which is adapted to synchronize the sewing machine and the driving motor in view of the right stop positions.

These machines therefore require a very special motor and in addition further means on the sewing machine per se. Furthermore, in practice these sewing machines still have the possibility that notwithstanding the synchronizing measures taken, the machine may still have two different stop positions, namely one in which the needle stands in the highest position and one in which the needle stands in the lowest position. Therefore, still further additional means are necessary for enabling the further rotation of the main spindle to the next stop position when the machine stops in the undesired position. This, however, brings about complications, since, when the machine stops in the wrong position, the operator has to carry out additional manipulations which take time, so that the time gained by the stopping in a definite position of the main spindle, is at least partly lost again. Besides, the special motors with the further necessary equipment are expensive, so that the whole equipment for the sewing machine makes the machine considerably more expensive.

The main object of the invention is to overcome these drawbacks.

According to the invention this is obtained by coupling the rope or belt pulley with the main spindle of the machine by a friction coupling which is controlled in such a manner that it is and remains coupled during starting and during the normal operation of the driving motor, but is released or declutched after switching off the driving motor, and at the end of the slowing down period of the main spindle is brought in the coupled position again in or at least in one definite position of the main spindle at standstill or practically standstill of the driving motor, so that the main spindle is rapidly braked and arrested. Thus, it becomes possible to use the sewing machine with a normal sewing machine motor, without additional mechanisms, except the usual provisions for the use thereof with a sewing machine. Also, the synchroniser on the main spindle of the sewing machine is no longer present and the main spindle only requires a relatively simple coupling mechanism with built-in automatic control means. This enables at the same time to obtain the advantages of stopping in a definite position, and therefore a time gain, by doing away with the necessity of bringing the needle each time after stopping of the sewing machine for instance in the highest position for removing the work piece, and the dependency of a particular construction of the driving motor is avoided, which is also 3,Z@4,59Z Patented Sept. 7, 1965 highly advantageous in view of the repairs which may become necessary.

In practice, the rope or belt pulley is appropriately coupled with the main spindle by means of an electromagnetic coupling wherein the driven coupling part is in turn coupled with the main spindle by a claw coupling having tangential play. The coupling further includes a switch in the driven electromagnetic coupling part which is controlled by the relative movements of the driven electromagnetic coupling part with respect of the claw coupling part which is rigidly connected with the main spindle during variations of the speed, as well as a centrifugal switch, which two switches lie in the exciting circuit of the electromagnetic coupling which is fed. through collector rings on the driven electromagnetic coupling part which in addition carries a further closed contact ring and a contact strip extending on at least a part of the circumference of such coupling part, and which contact elements can establish the coupling of the main spindle in the desired position with the driving pulley when the centrifugal switch is closed and the driving motor stands still. In this construction, the main spindle is directly arrested in a definite position, more particularly e.g. the position in which the needle stands at the highest position, in a very favorable manner by coupling with the driving motor which stands still and is braked, and said stop position is mainly determined by the contact strip extending on a part of the circumference of the electromagnetic coupling part, independently of the transmission ratio between driving motor and rope pulley, yet without fail a right stop position is always obtained.

Without having to sacrifice the important advantages in any respect, it is also possible to give the main spindle a second stop position, lying diametrically opposite the first stop position when the electromagnetic coupling part is provided with two contact strips, e.g. diametrically 0pposite one another, while the internal connections of these contact strips can be established at will by an operating switch arranged at the outside of the electromagnetic coupling part to one or the other or to both contact strips. This connection to the two contact strips will naturally only be used when stopping with the needle in the highest or in the lowest position sufiices for the work to be done. By these simple additional provisions, however, a sewing machine can be obtained which can be driven in the usual manner by an arbitrary driving motor but, contrary to the ordinary sewing machines, can be stopped after each working period with certainty that is will always be in one of two possible stop positions.

According to a further feature of the invention, the electrical circuit of the electromagnetic coupling is appropriately fed by direct current which can be obtained, for example, from a rectifier connected to the normal electric light system. The direct current feeding gives a constant and noiseless operation of the coupling without any vibrations.

In order to be able to keep the tangential play of the driven electromagnetic coupling part as small as possible and to reduce nocking of the mechanism during the switching on and switching off operations as far as possible, appropriately the switch reacting on the direction of the tangential forces is a micro-switch. A very little tangential play then sufiices for an absolutely reliable operation.

The invention will now be further elucidated with reference to an example of performance shown in the drawing, in which:

FIG. 1 shows a side elevation of the driving end of the main spindle of a sewing machine with rope or belt pulley mounted on such spindle and electromagnetic coupling according to the invention,

FIG. 2 an axial cross-section of the device according to FIG. 1,

FIG. 3 a cross-section on the line III-III in FIG. 2, in which the switches and the electrical connections arranged in this coupling part are diagrammatically indicated, and

FIG. 4 an electric wiring diagram of the device according to the invention.

In the drawing 1 is a sewing machine frame out of which projects the driving end of the main spindle 2. On this end of the main spindle a sleeve 3 is mounted which carries a flange 4 at one end, in which at three places a radial screw boring 5 for a set screw 6 is made. Around the sleeve 3 at the inner side of the flange 4, three cams 7 are arranged for fitting with some play, more particularly tangential play in appropriate recesses 8 of a driven electromagnetic coupling part 9 mounted rotatably around the sleeve 3. This driven electromagnetic coupling part is formed at the rear side, that is, at the side of the flange 4 of the sleeve 3, with a recess 10 in which a centrifugal switch 11 and a micro-switch 12 are arranged. This recess is closed at the rear side by a ring-shaped cover plate 13.

At the other end the coupling part 9, which for example, may be plastic, is provided with a ring-shaped recess in which an exciting coil 14 is arranged. Opposite this end of the driven electromagnetic coupling part lies the driving coupling part 15 defined by a flat disc of magnetic material, more particularly weak iron, and which disk is rigidly secured to rope pulley 17, preferably of plastic,

by means of fixing screws 16. The pulley and the disc 15 are mounted in a freely rotatably and axially displaceable manner on the sleeve 3 and prevented from sliding off axially from the sleeve 3 by a screw 18 threaded into the free end of the main spindle 2 and serving with the head 19 as a safety device for the rope pulley. In the outer surface of the driven coupling part 5! three contact rings 20, 21, 22 are arranged and extend about the whole circumference of the coupling part a contact strip 23 extends about only a relatively small part of the circumference. These contact elements to 23, which appropriately are bronze for example, cooperate with sliding contacts 20'-23' arranged, according to FIG. 1 on a support 24 attached to the machine frame 1. Of these sliding contacts, the ones cooperating with the ring 22 and the strip 23 are mutually interconnected as is shown in FIG. 4 at 25, while the sliding contacts cooperating with the contact rings 20 and 21 are connected with the terminals of a rectifier system 26 which is fed, e.g. from the city lighting system, through the terminals 27, 28.

Motor 40 is provided with a spindle :1 which carries a pulley 42 at one end and a rope or belt 43 is trained over the pulleys 17 and 42. The motor is provided with a suitable automatic brake shown diagrammatically at 4-4 and as soon as the motor current is interrupted, the automatic brake comes into action to brake the motor.

The current can be supplied in a known manner via a regulating resistance whereby the motor speed can be controlled with the assistance of a treadle.

The above described arrangement operates as follows:

When the driving motor 40 is switched on, the rectifier system 26 already receiving current through the net connection 27, 28, closes a circuit from the plus terminal of the rectifier 26 through the slip ring 21 to the exciting coil 14 and then through the leads 29 and 30 to the contact strip 23 and thence through the interconnection 25 to the slip ring 22 the lead 31, centrifugal switch 11 resting on the inner contact or rest contact 32, the leads 33 and 34, through the slip ring contact 20 and the lead 35 to the minus terminal of the rectifier system. The electromagnetic coupling is therefore in the coupled position and the driving motor directly drives the main spindle 2 by the rope 43, pulley 17 and the coupling 9, 15. At the beginning of the movement, the coupling part 9 is rotated with respect to the sleeve 3 as far as the play between the parts 7 and 8 permits such rotation. This rotation means that the micro-switch 12 is immediately operative whereby a direct path is established from the exciting coil 14 through the lead 36, switch 12, and the lead 34 so that when the interconnection 25 between the ring 22 and the strip 23 is interrupted by the rotation, the electromagnetic coupling remains excited and the driving motor can con tinue to drive the sewing machine. When the speed of the sewing machine increases, the centrifugal switch 11 closes on the contact 37 whereby a second direct path is expected between the exciting coil 14, lead 29, the centrifugal switch 11, lead 33 and the lead 34. This connection is necessary for ensuring that during working at normal speed of the motor, the possible swinging of the coupling part 9 with respect of the sleeve 3 and the opening of the microswitch 12 will have no effect on the operation of the electromagnetic coupling. This coupling thus remains operative with certainty, and also during the normal operation.

When, however, the motor switch is opened, which otherwise lies in a separate electric circuit with the driving motor, the driving motor is switched off, runs out and is braked. Then, immediately after the switching off of the motor switch and during the braking, a relative movement of the coupling part 9 with respect of the sleeve 3 will take place by which the main spindle of the sewing machine tends to lead the drive whereby the micro-switch 12 is opened. The current path through the lead 36 is then broken for the current but the centifugal switch 11 is still closed and the electromagnetic coupling remains coupled. When the speed of the main spindle decreases by the braking of the driving motor 40 and has reached a predetermined value, e.g. between and 200 revolutions per minute, the centrifugal switch drops on its rest contact 32. At this moment, the electromagnetic coupling 9, 15 no longer receives current and therefore it is declutched so that the main spindle can rotate independently of the pulley and the driving motor. The driving motor and the pulley are meanwhile further braked and stopped. When the contact elements 22 and 23 are contacted with the slip contact elements interconnected by the leads 25, the electromagnetic coupling 9, 15 is suddenly closed again and therefore the sewing machine is also suddenly stopped and the main spindle is then coupled with the driving motor which is braked. The contact strip 23 is arranged at such a place that, for example, the needle stands in the highest position when the strip is connected with the slip ring 22 by the lead 25 whereby the sewing machine will always and exclusively be stopped in the desired position and will be kept and arrested in this position until the driving motor is again activated.

When still a second definite position is desired, in which it is possible to stop the sewing machine, a second contact strip 23a can be arranged in the tangential path of the contact strip 23 on the driven electromatic coupling part 9 on the right place, namely for stopping with the needle in the lowest position diametrically opposite the contact strip 23. For preventing the machine from getting to two stop positions, the contact strips can be connected alternately to the lead 29 with the aid of a switch. The switch can, if desired, also be carried out in such a manner that both contact strips can be connected simultaneously with the lead 29 so that at will, an arbitrary stopping in positions lying, for instance apart becomes also possible. The switch necessary for this purpose may be arranged for actuation by hand with an operating member projecting to the outside from the electromagnetic coupling part 9 at one or two sides.

What I claim is:

1. In a sewing machine, particularly an industrial sewing machine, a main spindle for the sewing machine, a driving motor having a shaft, automtaic brake means for the motor, pulleys for said spindle and shaft, a belt trained over said pulleys for driving said spindle, coupling means between the spindle pulley and the spindle adapted to couple the spindle pulley to the spindle, said coupling means including an electromagnetic part and a claw part with said claw part being connected to the spindle to.

provide tangential play between said mangetic part and said claw part, a switch on said electro-magnetic part controlled by the relative movements of the electro'magnectic part with respect to the claw part, a centrifugal switch on said electro-magnetic part, an exciting coil in the electro-magnetic part, a circuit in which said coil and said switches are located, collector rings on said electromagnetic part through which said circuit is fed, a closed contact ring on said electro-magnetic part, and a contact strip extending about at least a part of the periphery of said electro-magnetic part with said contact ring and strip completing a circuit to said coil to establish the coupling of the pulley on the spindle with the spindle.

2. In a sewing machine, particularly an industrial sewing machine, a main spindle for the sewing machine, a driving motor having a shaft, automatic brake means for the motor, pulleys for said spindle and shaft, a belt trained over said pulleys for driving said spindle, coupling means between the spindle pulley and the spindle adapted to couple the spindle pulley to the spindle, said coupling means including an electro-magnetic part and a claw part with said claw part being connected to the spindle to provide tangential play between said magnetic part and said claw part, a circuit in which said coil and said switches are located, collector rings on said electro-magnetic part through which said circuit is fed, a closed contact ring on said electro-magnetic part, a contact strip extending about at least a part of the periphery of said electromagnetic part with said contact ring and strip being connected to establish the coupling of the pulley on the spindle with the spindle, a second contact strip extending about at least a part of the periphery of said electro-magnetic part and being located diametrically opposite said first-mentioned contact strip, and an actuating switch connecting said contact strips to said electro-magnetic part for stopping the machine at a predetermined position.

3. The sewing machine as claimed in claim 1, in which said first-named switch is a micro-switch.

4. The sewing machine as claimed in claim 1, in which said circuit is fed with direct current.

References Cited by the Examiner UNITED STATES PATENTS 2,692,667 10/54 Bliedung et al. 112219 2,942,564 6/60 Larys et al. l12219 2,967,499 1/61 Cohen 1122l9 ROBERT V. SLOAN, Primary Examiner.

DAVID J. WILLIAMOWSKY, JORDAN FRANKLIN,

Examiners. 

1. IN A SEWING MACHINE, PARTICULARLY AN INDUSTRIAL SEWING MCHINE, A MAIN SPINDLE FOR THE SEWING MACHINE, A DRIVING MOTOR HAVING A SHAFT, AUTOMATAIC BRAKE MEANS FOR THE MOTOR, PULLEYS FORO SAID SPINDLE AND SHAFT, A BELT TRAINED OVER SAID PULLEYS FOR DRIVING SAID SPINDLE, COUPLING MEANS BETWEEN THE SPINDLE PULLEY AND THE SPINDLE ADAPTED TO COUPLE THE SPINDLE PULLEY TO THE SPINDLE, SAID COUPLING MEANS INCLUDING AN ELECTROMAGNETIC PART AND A CLAW PART WITH SAID CLAW PART BEING CONNECTED TO THE SPINDLE TO PROVIDE TANGENTIAL PLAY BETWEEN SAID MANGETIC PART AND SAID CLAW PART, A SWITCH ON SAID ELECTRO-MAGNETIC PART CONTROLLED BY THE RELATIVE MOVEMENTS OF THE ELECTRO-MAGNECTIC PART WITH RESPECT TO THE CLAW PART, A CENTRIFUGAL SWITCH ON SAID ELECTRO-MAGNETIC PART, AND EXCITING COIL IN THE ELECTRO-MAGNETIC PART, A CIRCUIT IN WHICH SAID COIL AND SAID SWITCHES ARE LOCATED, COLLECTOR RINGS ON SAID ELECTROMAGNETIC PART THROUGH WHICH SAID CIRCUIT IS FED, A CLOSED CONTACT RING ON SAID ELECTRO-MAGNETIC PART, AND A CONTACT STRIP EXTENDING ABOUT AT LEAST A PART OF THE PERIPHERY OF SAID ELECTRO-MAGNETIC PART WITH SAID CONTACT RING AND STRIP COMPLETING A CIRCUIT TO SAID COIL TO ESTABLISH THE COUPLING OF THE PULLEY ON THE SPINDLE WITH THE SPINDLE. 